Error "Unable to create channel of type 'dahdi' "

Hi ,

i want to call from “xlite” to “dahdi” Trunk
i have TDM401P
but i get this errors in asterisk CLI:

Executing [12345@to-external:1] Dial(“SIP/222-b761eb00”, “dahdi/g0/12345”) in new stack
[Oct 16 14:11:15] WARNING[17124]: app_dial.c:1275 dial_exec_full: Unable to create channel of type ‘dahdi’ (cause 34 - Circuit/channel congestion)
== Everyone is busy/congested at this time (1:0/1/0)

this is my conf files :

sip.conf

[general] context=default srvlookup=yes port=5060 disallow=all allow=alaw allow=ulaw [222] type=friend username=222 secret=123456 host=dynamic context=to-external
extensions.conf

[globals] CONSOLE=Console/dsp Gateway=dahdi/g0 [to-external] exten => 12345,1,Dial(${Gateway}/${EXTEN})

chan-dahdi.conf

[channels] usecallerid=yes callwaiting=yes usecallingpres=yes callwaitingcallerid=yes threewaycalling=yes transfer=yes canpark=yes cancallforward=yes callreturn=yes echocancel=yes echocancelwhenbridged=yes group=1 callgroup=1 pickupgroup=1 ;;; line="3 WCTDM/4/2 FXSKS (EC: KB1)" signalling=fxs_ks callerid=asreceived group=0 channel => 3 context=to-external ;;; line="4 WCTDM/4/3 FXSKS (In use) (EC: KB1)" signalling=fxs_ks callerid=asreceived group=0 channel => 4 context=to-external

can you help me
thank you in advance for any help ,